If $x \diamond y = x(y-6)$ and $x \star y = 5x-4y$, find $0 \diamond (2 \star 0)$.
First, find $2 \star 0$ $ 2 \star 0 = (5)(2)-(4)(0)$ $ \hphantom{2 \star 0} = 10$ Now, find $0 \diamond 10$ $ 0 \diamond 10 = 0$ $ \hphantom{0 \diamond 10} = 0$.